1. Field of the Invention
The present invention relates to a method of manufacturing a housing for electronic parts, and more particular, to a method of manufacturing a housing for high-frequency electronic parts of a non-reciprocal circuit element such as isolators, or the like.
2. Background Art
Generally, a concentrated constant type isolator or circulator used in a relatively high frequency band, such as UHF, VHF, SHF, or the like, functions to pass a signal only in a direction of transmission and prevent transmission in an opposite direction, and is widely adopted in transmitting circuits of mobile communication equipments such as portable telephones or the like.
The isolator is mainly composed of, for example, a magnetic assembly made of ferrite and a central conductor, and a permanent magnet, these elements being received in a housing. Ordinarily, silver plating with low electrical resistivity is applied to surfaces of the housing so as to convert noise into eddy current to discharge the same.
Such housing for isolators is manufactured by preparing, for example, a metallic housing part support, in which a plurality of housing parts are successively connected to a frame through connections, and separating the respective housing parts after silver plating is applied to the housing part support. Since the plurality of housing parts are collectively subjected to plating processing in a state of being connected to the frame, it is possible to plate the plurality of housing parts at a time, and workability at the time of plating processing is prevented from being lowered particularly in the case where the housing is small in size.
Since housing parts are subjected to plating and then cut off from a frame in a conventional method of manufacturing a housing for isolators, however, cut surfaces are not plated and left as they are. When plating remains incomplete, there is a fear that it becomes difficult to eliminate influences of high-frequency noise. Also, in the case where cut surfaces being not plated make terminals of an isolator, there is a fear that when the isolator is soldered to a circuit board, soldering becomes worse to cause contact failure.